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<concept id="GUID-B77702FA-7385-51A0-986F-7667669CBDB2" xml:lang="en"><title>Guide

to Optimising Performance</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This document highlights areas to investigate as part of a system-wide

performance optimization process. </p>

<section><title>Introduction</title> <p>During development much attention

is devoted to functionality. It is typically only at the later stages of development

that performance (speed, RAM use, power consumption) becomes an issue. This

is inevitable for many good reasons. </p> <ul>

<li id="GUID-32A6D5A9-4A2C-5EC0-B602-98C0B14A9487"><p>Performance cannot be

easily or usefully assessed until a device or system nears completion. </p> </li>

<li id="GUID-572885AD-64E4-5963-AA44-7883239E33AA"><p>Performance is often

affected by interactions between components. </p> </li>

<li id="GUID-BF3A5F0F-10A1-5E44-8DA0-0A1089705B85"><p>Performance is hardware

related. </p> </li>

<li id="GUID-2363FD02-FD50-5837-A719-E976925C2F29"><p>Optimizations can result

in less easily maintained code. </p> </li>

<li id="GUID-6016203A-D493-5829-8A33-BB28DD21DDC3"><p>A few worthwhile optimizations

are much more efficient than many which have little impact. </p> </li>

</ul> <p>This does not mean that improving or optimizing performance should

only be considered as a single activity to be performed towards the end of

a development project. Good practise and forward thinking in all aspects from

the outset are the most important contributors to producing high-performance

products. </p> <p>The Symbian Developer Library is full of advice on how to

write fast and efficient code and how to configure your software and hardware

for optimized performance. </p> </section>

<section><title>Objectives</title> <p>Performance improvement or optimization

may be described as achieving some or all of the following: </p> <ul>

<li id="GUID-62821E16-8F93-5C56-ADD7-B1D1ACA08AFB"><p>Increased execution

speed. Applications and processes perform or appear to perform tasks in less

time. </p> </li>

<li id="GUID-DEB5147F-3932-56F4-8E46-435A2A059B38"><p>Reduced start up time.

Devices are ready for use more quickly after being switched on. </p> <p><xref href="GUID-AF30D941-BFD8-5260-9588-C5DA6983F558.dita">System Starter</xref>  </p> </li>

<li id="GUID-83720AE2-A308-59ED-8C20-FC7981486D4C"><p>Efficient ROM and RAM

use. ROM and RAM cost money. </p> <p><xref href="GUID-EFC99FD5-4EC2-5B9E-AE03-FE66D1ABF8A8.dita">Optimising

Compressed ROMs</xref>  </p> </li>

<li id="GUID-4554E6D0-76D7-589F-924A-9724074F8A0F"><p>Reduced power consumption. </p> </li>

</ul> </section>

<section><title>Assessment and Measurement</title> <p>Making changes to functioning

code is a time consuming and high-risk activity. Before making any changes,

therefore, you must be confident that you are likely to have a significant

beneficial impact and that you will be able to measure and quantify it. </p> <p>The

Symbian platform includes tools and supports techniques that enable you to

analyze, monitor and measure the performance of your system or device. </p> <p>The <xref href="profiler.htm" scope="external">Symbian Platform Sampling Profiler</xref> </p> <p><xref href="GUID-BB174A7C-9B72-55C8-8C8A-F5FB14AB3607.dita">Hardware Debugging Tools</xref>  </p> <p><xref href="GUID-A3E77067-7982-5803-A274-0C8F2562B483.dita">General purpose logging (UTRACE)</xref>  </p> </section>

<section><title>Actions and Activities</title> <p><b>Configuration</b> </p> <p>The Symbian platform and many of its components support various build-time

configuration parameters. These include settings in configuration and initialization

files, macro definitions and patchable constant values. </p> <p><xref href="GUID-7E401451-16EB-515B-88B2-4D0D2D6C7A57.dita">Adjustable

Performance Configuration</xref>  </p> <p><xref href="GUID-B526BA3A-14E4-53B4-9382-437475A1C8A4.dita">List

of Patchable Constants</xref>  </p> <p><b>Coding

Practise</b> </p> <p>There are many aspects of coding practise that can result

in performance variations. Though such differences might appear small, performance

bottlenecks can occur where a piece of inefficient code is executed repeatedly.

By identifying where bottlenecks exist you target specific areas of code that

have a significant impact on performance. </p> <p><xref href="GUID-49645D0A-AEA4-5D61-A6F3-633D80DCFD5B.dita">Application

Performance</xref>  </p> <p><xref href="GUID-12FF05BE-F06E-58F0-909D-05CB6F7FA03E.dita">Code

Efficiency</xref>  </p> </section>

<section><title>Further Reading</title> <p>The following documents, located

in other sections of the library, discuss performance and optimization issues

relating to particular components of the operating system. </p> <ul>

<li id="GUID-EF06353C-E907-507E-8468-DC373D6E89AB"><p>Calendar: <xref href="GUID-94AC5E9C-146D-5FE7-B7B6-44AA139A6012.dita">Speeding

up Agenda Application Start-up How-To Document, in the Agenda Model engineering

documents section</xref>  </p> </li>

<li id="GUID-779BAF64-10F9-549D-AAE2-B8A13B923A13"><p>Contacts: <xref href="GUID-2E1DCE15-2F35-57E4-A279-18D1A3AB4BD3.dita">Speeding

up Contacts Application Start-up How-To Document, in the Contacts Model engineering

documents section</xref>  </p> </li>

<li id="GUID-9B7C9702-5877-51B1-87D9-573F6D9A1430"><p>Plugin Framework: <xref href="GUID-85AE95DD-D8C0-5F38-9A98-2F92328162E7.dita">Using ECOM and plug-ins in

phone ROMs</xref>  </p> </li>

<li id="GUID-97F6CBB4-928F-5EE2-857B-15999502AB98"><p>Various components: <xref href="GUID-C6C77895-91E8-5BBF-8D77-0DF6F92F1223.dita">System-level engineering

documents</xref>  </p> </li>

</ul> </section>